Fuel preheater



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L. l. ALDRICH FUEL PREHEATER Original Filed Feb. 2, 1939 Aug. 15, 1944.

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atentc ug. E5, i344 FUEL PBEHEATEB Loyd I. Aldrich. Wyoming, Ill.

Original application February 2, 1939, Serial No. Divided and thisapplication August 18, 1941, Serial No. 407,308

Claims.

My present invention relates to a preheater for fuel oil for use inconnection with an oil burner system particularly adapted forefficiently burning heavy gravity fuel oil, such as commonly known onthe market as No. 4 or No. 5v oil, the present application being adivision of my copending application Serial No. 254,197, filed February2, 1939, now Patent No. 2,263,833.

One object of my invention is to preheat heavy fuel oil to a temperatureadjacent the flash -point thereof so that its viscosity is changed tothe neighborhood of ordinary light oils now used for conventional highpressure burners, the preheater illustrated being simple and inexpensiveto manufacture and including a strainer having an easy cleaning feature.

A further object is to provide a preheater wherein the strainer islocated with respect to the heating means so that the incoming oil isthereby heated and thus flows more readily through the interstices ofthe fuel strainer.

A further object is to provide a fuel strainer in the form of aforaminous cylinder, open at one end and closed at the other end, thecylinder being removably positioned with respect to a wall of apreheater tank and so associated with an inlet pipe that the incomingfue! oil is deposited inside the foraminous cylinder so that when thestrainer vis removed' all of the foreign material is removed :with it,and may then be readily cleaned therefrom.

Stili a further object is to provide control means which effectsmaintenance of the oil in the preheater at a substantially uniformtemperature, there being provided a control switch responsive to thetemperature of the oil in the preheater for automatically controlling anelectric heating unit inthe preheater tank.

With these and other objects in view, my invention consists in theconstruction, arrangement and combination of the various parts of mydevice whereby the .objects contemplated are attained, as hereinaftermore fully set forth, pointed out in my claims and illustrated in theaccompanying drawing, in which:

Figure 1 is a sectional view through a fuel oil preheater embodying myinvention and showing it connected with an oil burner system of the kindshown in my previously referred to copending. application.

Figure 2 is a sectional view on the line 2-2 of Figure 1, showing theconnection of a fuel inlet to a strainer means; and

Figure 3 is a sectional view on the line 3-3 of Figure i showing on areduced scale a partial plan view of one end of the preheater and a fuelstrainer associated therewith.

On the accompanying drawing I have used the reference character B toindicate generally a burner mechanism, and P a preheater for the fueloil supplied thereto. The burner B is of the gun type shown in mycopending application, having a blast tube I0 to which air is suppliedand a nozzle l2 from which atomized oil is d scharged. 'I'he oil issupplied to the nozzle I2 through a pipe i3 connected with an oil pumpIl receiving oil from an outlet pipe i4 of the preheater P. A star-tingby-pass pipe Ii by-passes the heated oil from the preheater through asole noid valve SV and return. lines I1 and i3 to a return nipple' I9 ofthe preheater B. Also, oil is normally returned through a pipe 23 to thepipe I3 as the pump il pumps oil in excess of that required by thenozzle l2..

Since 4the burner and its operation do not form any part of my presentinvention, I believe the foregoing description is suilicient to indicatethe type of installation used with my preheater P. Reference is made toiycopending. application for the full details of the burner B and itsoperation. My preheater P includes an oil tank T, consisting of acylindrical wall v2| and end walls 22 and 23 retained in position by tierods 2| with` suitable gaskets 25 interposed between the vheads and thecylinder 2|. The heads 2 2 Vand 23 are provided with extensions 26(preferably three or four for each head) and an outer cylindrical casing21 surrounds the tank T and engages the extensions. The outer casing 2lhas end plates 28 and 29, and between the outer casing and the tank Theat insulating material 30 is provided to prevent dissipation of heatfrom the tank T and thereby cause operation of the structure of thepreheater at maximum emciency.

The head 22 is provided with a bore 3i adapted to receive a strainer'Sincluding a sleeve-like element 32 received in the bore 3i. The bore 3|has an enlarged annular groove 33 adapted to receive oil from a supplypipe 34 which is preferably fed by gravity from a storage tank (notshown). The element 32- terminates in a flange '34* secured to the tankhead 22 by cap screws or the like 35,` with a suitable gasket 36interposed between the head and the flange. The element 32 is providedwith a plurality of openings 31 through which the oilvilows to theinterior of a tubular screen 38. The inner end of the screen is closedby a plug 39.

The tank head 23 is provided with a bore 40 ladapted to receive aheating unit H. The unit H is preferably of the electrical typeincluding a resistance element shown diagrammatically at 4I encased in ametal sheath 42. The sheath 42 is secured to a hub,43 which terminatesin a flange 44 adapted to be secured to the head 23 by cap screws or thelike 45, with a suitable gasket 46 interposed between the flange and thehead. A terminal support 41 has terminals 48 and 4S for the heatingelement 4 I. The outlet pipe I5 communicates with the bore 46 by apassageway 50. It will be noted that the hub 43 is of such size relativeto the bore 40 that oil from the tank T must pass over the heater H uponleaving the tank and flowing to the pump I4.

Connected with the top of the tank T is a vent pipe 5I which extendspreferably back to the top of the storage tank so that any air trappedin the preheater P may be allowed to escape. Within the tank T I providea capillary bulb 52 and a capillary tube 53 connecting it with a controlswitch S. The switch S', as described, is responsive to the temperatureof the oil in the tank T.

Practical operation In the operation of my preheater, No. 4 or No. 5 oilis extremely heavy and at room temperature cannot be passed through afine screen, nor can it be properly atomized nor pumped through smallcopper tubes with any degree of assurance that it will flow uniformly. Iaccordingly have the switch S set for operation at a relatively hightemperature (190 or 200). I have found that this is satisfactory for anoil that has a flash point of 235 as it reduces the oil to the desiredviscosity for eilicient atomization at the nozzle tip. and theconsistency of the oil is then such that it will pass through a veryfine screen (1Z0-mesh) Such a screen will effectively strain out allimpurities and will require cleaning out not more than once or twice aseason with the usual run of oil.

When the heater H brings the temperature of the oil in the tank T up tothe point where the switch S cuts out, there will be a discontinuance ofthe heat in the heater H, and the switch will thereafter operate tomaintain the temperature of the cil in the preheater substantiallyconstant, cutting in when the temperature recedes below the setting ofthe switch and cutting out when it exceeds the temperature at which theswitch is set.

When a, burner operation occurs, the preheated oil is first pumped tothe nozzle I2, but not through it. Such oil then pasess back through thepipes IG-Il-IB-I 9 to the tank T, the valve SV being open at that time.After a time period, determined by the length of time it takes for theoil passages to become thoroughly heated, the solenoid valve SV closes,and pressure is built up back of the nozzle I2 to a predetermineddegree, which opens the nozzle and permits the oil to be atomizedtherethrough. The excess oil, however, is by-passed back through20-I8-I9 to the tank T, and thus by having the pump I4 supply more oilthan required by the nozzle I2, the preheated oil is continuouslycirculated to keep the temperature of the oil passageways at the desiredpoint for eiiicient operation in connection with heavy oil.

The preheater also heats the oil so that it can be eiiiciently strainedthrough a fine screen, which contributes materially to the effectiveoperation of an oil burner of the kind herein disclosed when burninghigh gravity oil. Recently, there has been a movement toward the removalof 'lighter grades of oil from the market as a fuel for oil.

burners, as these lighter grades can be cracked for gasoline. My systemmakes possible the use of very heavy oil that is unsuitable for crackingprocesses, and utilizes the effective preheating of the oil and asubsequent utilization of the preheated oil in such manner that nothingbut thin viscosity oil is sprayed from the nozzle, thus increasing theemciency of combustion and diminishes the possibility of formation ofcarbon. Furthermore, my preheater conditions the oil so that it can befinely atomized at relatively high pressures or 175 pounds per squareinch), and I am able to secure greater heating from a given quantity ofoil as heavy gravity oil is capable of delivering more B. t. u.s thanlighter oils.

The strainer S being located adiacent the heater H, and preferably Justabove it, insures that the strainer will be well heated at all times, sothat the incoming oil is also heated and may thereby pass readilythrough a fine mesh strainer. The strainer arrangement is also such thatthe oil is delivered to the interior thereof, and, accordingly, anysediment f or foreign matter strained from the oil is contained withinthe strainer. Thus, when the strainer is removed by removal of the endmember 2l of the preheater, the insulation in front of the flange 34land the cap screws 35, the strainer S may then be removed and theSediment will remain in it. The sediment can then be readily washed outthrough the openings 31, and the strainer replaced. Cleaning thestrainer is therefore a comparatively simple operation, and there isassurance that none of the sediment will be left in the tank T, nor willit fall into the tank as the strainer is removed.

The tank may be drained when desired by removing a cap 54 from a drainpipe 55.

Some changes may be made in the construction and arrangement of theparts of my device without departing from the real spirit and purpose ofmy invention, and it is my intention to cover by my claims any modifiedforms of structure, or use of mechanical equivalents, which may bereasonably included within their scope.

I claim as my invention:

1. A fuel preheater for use in an oil burner system having a nozzle andmeans for pumping oil from said preheater to said nozzle, said preheaterhaving an inlet, heating means in said preheater for maintaining thefuel therein at a substantially constant predetermined temperature, saidpreheater including a strainer adjacent said heating means and therebyalso maintained at said substantially predetermined temperature, saidstrainer being located between said heating means and said inlet toreceive incoming fresh oil before it is heated, said strainer includinga foraminous cylinder closed at one end and open at its other end, saidother end receiving the fuel whereby sediment and the like in the fuelis deposited inside of the formanious cylinder, and means for removingsaid foraminous cylinder from said preheater to remove such sedimenttherefrom.

2. An oil preheater for an oil burner comprising a tank, heating meansin said tank along the bottom thereof, an oil inlet to one end of saidtank, a pocket-like strainer removably positioned in said tank adjacentsaid oil inlet and arranged relative thereto for reception of oil intothe interior of the strainer from the oil inlet, said tank having anoutlet at the opposite end thereof from which oil may be pumped fromsaid preheater to the oil burner.

3. A fuel oil preheater comprising a tank, a shell surrounding saidtank, insulating material between said tank and said shell, a strainerremovably positioned in one wall oi said tank, said strainer having anopen end and a closed end, said wall of said tank having an inletcommunieating with said open end whereby sediment from the oil isdeposited inside of the strainer and may be removed with the strainerfrom the tank, heating means in said preheater having a portionpositioned adjacent said strainer to heat the fuel oil flowing thereintosaid tank having an outlet and said heating means having another portionlocated in the line of oil flow from said strainer to said outlet.

4. In an oil preheater, a tank, heating means therein having endportions and a center portion, and a pocket-like strainer therein and1ocated in the zone of heat from one of said end portions, an oil inletto the interior of said strainer, said tank having an outlet adjacentthe other of said end portions, a pump for pumping oil from said outlet.said center portion being in the path oi the oil from said strainer tosaid outlet, and a nozzle receiving oil from said pump.

5. A fuel tank for use in an oil burner system having a nozzle and meansfor pumping oil from said tank to said nozzle, said tank having aninlet, an outlet and a return inlet from the pumping means, a strainerin said tank to receive incom ing fresh oil, said strainer including aforaminous cylinder closed at one end and open to said inlet at itsother end, said other end receiving the fuel whereby sediment and thelike in the fuel .is deposited inside of the Ioraminous cylinder,

means for removing said foraminous cylinder from said tank to clean suchsediment therefrom and heating means in said tank and located in the oilpath from said strainer to said outlet, said return inlet returning oilinto said path ad jacent said strainer whereby the return oil isreheated by a portion of the heating means between said strainer andsaid outlet.

` LOYD I. ALDRICH.

